Way back in summer 2008, AMD launched the Radeon HD 4870. At the time, it seemed like PC graphics would never be the same again. Here was a £200 3D card from AMD that gave Nvidia boards selling for £350 a serious scare. It was, at the time, astonishing value for money and an instant hit.
Even better, we were promised the 4870 wasn't just a one off. At the launch event, AMD said it had fundamentally reassessed the graphics market following the debacle of the oversized and underperforming Radeon HD 2900. No longer would AMD engage with Nvidia in a futile contest for ultimate performance bragging rights. Instead, AMD would aim to deliver maximum value around the £200 price point.
At any moment in the GPU product cycle, AMD probably wouldn't offer the fastest single GPU on the planet, but its top graphics chip wouldn't be far off the best and would be a damn sight cheaper. Put simply, the strategy worked.
The Radeon HD 4870 didn't pump out benchmark numbers quite as colossal as Nvidia's mighty GeForce GTX 280. But the actual in-game experience was very similar. And the 4870 was over £100 cheaper.
Fast forward to early 2011 and there's good news and bad news. The bad is that AMD hasn't quite stuck to its promise. With the launch of the Radeon HD 5870, AMD took a step back towards the traditional high-end graphics. The new GPU was big and it had a price to match north of £300.
Nvidia has since trumped the 5870, first with the ever so slightly underwhelming GeForce GTX 480 and then more comprehensively with the much improved GTX 580. Of course, the 580 is a £400 video card. In our book that makes it almost irrelevant.
But here's the good news. The spirit of the Radeon HD 4870 lives on. Expectations around the sub-£200 price point have been permanently lifted. The competition isn't just fierce, it's positively homicidal.
Both Nvidia and AMD offer a wide range of 3D chipsets highly optimised to deliver enormous bang for buck below £200. There may be faster cards. But none give you so much performance for each and every pound. The sub-£200 performance graphics card market isn't just the most competitive, it's also arguably the most intriguing.
The reason is that there's a fascinating contrast in styles with some boards based on cut-down versions of high-end chips and others being purpose-built for the job. A little further down the price range, cheaper boards based on smaller mid range graphics chips also offer spectacular value for gamers on a tighter budget.
Despite all this choice, there is one metric by which picking a £200 pixel pumper is pretty painless. Whichever 3D chipset you go for, from whatever graphics vendor or board maker, the race in terms of feature set is a dead heat.
All boards support the latest DirectX 11 multimedia API from Microsoft. You don't need to worry about game support for the foreseeable future. It also means, generally speaking, what matters is how fast these cards get stuff done, not the details of what they can do.
A choice of tessallator
While we're talking DX11, however, there are a few foibles worthy of further examination. Both tessellation and the Compute Shader are areas where AMD and Nvidia's graphics architectures diverge significantly.
The tessellator is a tough one to call simply because it's seen so little use in real games rather than tech demos and benchmarks. As for the Compute Shader, suffice to say if running non-graphics software, such as video encoding or image editing on your 3D card is likely to be a major factor for you, there are significant differences in GP-GPU support from the two main graphics vendors.
With all that stored in your data banks, it's time to weigh up the really important stuff. That'll be the price and performance.
This month, we've rounded up 10 bargainous boards all available for under £200. In fact, our ten pixel pumpers span a wide range from around £60 right up to the £200 cut off. Whatever your budget, there's something here to suit.
Pixel for under a ton
Our graphics grandstand begins with the cheapest chipset on test this month. On paper, Nvidia's GeForce GT 430 might seem rather feeble, after all, it only manages 96 of Nvidia's so-called CUDA cores (stream shaders to everyone else). The epic new GeForce GTX 580 has 512.
Predictably, the GT 430 looks puny by most other metrics, too. You only get 16 texture units compared with the 580's 64 units. Then there's 128-bit memory, which is traditionally a performance killer at high resolution and detail settings.
Possibly worst of all is the meagre total of four ROPs. These are the units that draw together all the work done by the entire graphics pipeline, give it all a final polish and spit the results out to your screen. The more ROPs you have, the more pixels your card can pump per cycle. A GeForce GTX 580 has 48 ROPs.
Still, even though the GT 430 inevitably seems anaemic next to the mighty 580, remember that not so long ago the best graphics cards you could buy were based on Nvidia's preposterously successful G92 GPU. The G92 chip sired several boards, including the GeForce 8800 GT and 9800 GTX. It was a DirectX 10 chip with just 128 shaders.
What's more, the GT 430 is a pukka DirectX 11 GPU complete with tessellation support. It also boasts an excellent 2D video feature set, including hardware acceleration for all the important video codecs as well as Flash 10 acceleration. It's a great little home theatre chipset in other words and offers tolerable performance for £50 and upwards, depending on memory configuration.
But it isn't a good option for a GP-GPU on the cheap. When the GT 430's stream shaders are operating in double precision FP64 mode, they only manage 1/12th the throughput compared to FP32. That's not a major issue for graphics or gaming. But it's a bit of a downer for GP-GPU.
Factor in the modest shader count and you have a 3D chipset that's best reserved for gaming and video playback.
Heading towards £100
Slightly higher up the price scale is AMD's Radeon HD 5750 chipset. Yours from around £75, this is where the serious 3D fun kicks in.
The 5750 is based on AMD's Juniper GPU. In this format, Juniper offers 720 of AMD's stream shaders, 36 texture units and 16 ROPs. That's not a bad spec sheet compared to the quickest single-GPU Radeon HD 5000 card, the 1,600-shader, 80-texture and 32-ROP HD 5870.
In our view, then, the 5750's only major weakness is its 128-bit memory bus. Admittedly, AMD specified some nippy memory: 4.6GHz GDDR5 chips. But in the end, there's no substitute for bus width.
Similarly, when it comes to stream shaders, AMD and Nvidia's architectures are not comparable. As a very rough rule of thumb, consider one of Nvidia's shaders as worth four of AMD's. That comparison is becoming a little more complicated with the arrival of AMD's new Radeon HD 6000 series. But we'll come to those chips later.
Next up is the Radeon HD 5770. Starting from a whisker over £100, the 5770 takes the Juniper GPU from the 5750 and unleashes its full potential. The shader count swells from 720 to 800 and you get another four texture units for a total of 40.
AMD has given the core clockspeed a healthy bump from 700MHz to 850MHz. On paper, the 5770 looks impressive. In many regards it matches the fastest chip from AMD's Radeon HD 4000 series and adds full DirectX 11.
As with the 5750, however, our main concern is the narrow 128-bit memory bus. Until recently, Nvidia had no answer to the Radeon HD 5700 series. At least, it didn't have a chip that could compete on price and performance while matching the 5700's DX11 feature set.
That changed with the arrival of the GeForce GTS 450 in September 2010. Based on Nvidia's GF106 GPU, itself a smaller derivative of the awesome chip that powers the GTX 580, it packs 192 shaders, 32 textures and 16 ROPs.
Like the 5700, its main weakness is a 128-bit memory bus, a feature made even more critical by Nvidia's choice of relatively slow 3.6GHz GDDR3 memory. If the Radeon HD 5700 and GeForce GTS 450 are where real graphics performance begins, the competition gets very serious indeed when you step up to the next rung of 3D boards.
Nvidia's GeForce GTX 460 was a little late to the DX11 party. But it made a major impact all the same. The headline figures are pretty impressive for an Nvidia board that can be had for as little as £125. Its 336 CUDA cores are joined by 56 texture units, a massive 32 ROPs and a healthy 256-bit bus.
Granted, the core and shader clocks of 675MHz and 1,350MHz are a little conservative. But the 460 has an awful lot of muscle for such an affordable board. It's all possible because Nvidia chose to dispose of some of the transistor-hungry GP-GPU optimisations for the GF104 chip that underpins the GTX 460. Like the GT 430 and GTS 450, FP64 operations also run at 1/12th FP32 speed.
The GTX 460's final foible involves its memory buffer. It's available in both 768MB and 1GB trim. In general, we wouldn't recommend any graphics card with less than 1GB. It's well worth stretching the extra £15 or so for the fatter 1GB board.
Entering second gen
Next up is the first of AMD's second generation DX11 cards from the new Radeon HD 6000 series. Or perhaps that should be AMD's DX11 generation 1.5.
The Radeon HD 6850 is very much a genuine member of AMD's new Northern Islands GPU family. However, despite its seemingly high-end branding it's not the Radeon HD 5800-killer we were expecting nor does it debut the new graphics architecture with symmetrical quad-ALU shaders we had been hoping for.
That only arrives with the upcoming Radeon HD 6900 and its more widely overhauled architecture.
Instead, it's best to think of the 6850 as being a very minor tweak of the Radeon HD 5000's existing shader architecture, also known as VLIW5. By some measures, the 6850 doesn't look terribly exciting. With just 960 stream processors and 48 texture units, its raw rendering power is only slightly up on the Radeon HD 5770.
However, it does have a couple of secret weapons. For starters it has a high-res friendly 256-bit memory bus feed by 4GHz GDDR5 memory. It also has improved tessellation performance.
The details are complex but mainly involve improved buffering and revamped tessellation shaders. The upshot is a doubling of tessellation performance at medium tessellation factors compared to the Radeon HD 5800 family. Wind the tessellation up to crazy levels, however, and the 6850's engine performs little better than the 5800s.
One other significant new feature that arrives with the Radeon HD 6800 series is an HDMI 1.4a port. Okay, that's hardly super exciting in itself. But it is part of a broader package that introduces stereoscopic 3D.
With the 6800, AMD is launching its take on stereoscopic 3D in the form of HD3D. The HDMI 1.4a interface is necessary for Blu-ray 3D support. Unlike Nvidia's 3D Vision, HD3D uses passive polarised glasses rather than active shutter lenses. That should make for a cheaper overall setup. Look out for PCF's take on HD3D later this year.
Cut-price GPU winners
Cutting a slightly odd figure in AMD's ever-expanding GPU range is the Radeon HD 5850. Based on the older Radeon HD 5800 series it lacks a few features compared to the shiny new 6800 series. It's also coming towards the end of its useful life, especially now the new Radeon HD 6900s make it look even more redundant.
But don't go thinking the 5850 has nothing to offer. Chips often deliver better value for money at the end of their innings. That definitely applies to the 5850 now that it can be had for £165.
With 1,440 AMD-style shaders, 72 texture units and 32 ROPs, it's still beefy even if its 725MHz core clock is a little slovenly. Thanks to its status as an outgoing flagship GPU, it also benefits from a full-width 256-bit memory bus.
The starting price of our final two contenders is pretty much on a par: around £185. Like the Radeon HD 5850, Nvidia's GTX 470 is in the process of being usurped by the GTX 570. And that means the 470 is much more affordable now than at launch last summer when it cost over £300.
Remember, this card sports Nvidia's monstrous Fermi GPU. Even with a few bits and pieces disabled, it still manages 448 shaders, 56 textures, 40 ROPs and a 320-bit memory bus. Make no mistake, despite modest core and shader clocks of 607MHz and 1,215MHz respectively, this is one serious pixel pumper.
However, the 470 looks like a blunt instrument, compared to AMD's new Radeon HD 6870. The 6870 is derived from the same Barts GPU found in the lesser 6850. For the 6870, Barts is unlocked: All 1,120 shaders are enabled and running at 900MHz, a hefty boost over the 6850's 775MHz core clock.
The 6870 also ups the texture count to 56 and has faster 4.2GHz GDDR3 memory on a 256-bit bus. It's a lean, mean DX11 machine. In fact, the 6870 represents an opposite approach to the heavy-hitting GTX 470.
It's just one fascinating battle in the wider war between AMD and Nvidia in the sub-£200 graphics market. It's a war in which there can be only one winner – that'll be lucky little ol' you.
